薄膜内杂质分布的分形特征

Fractal Distribution Character of Inclusions in the Films

薄膜中总会存在一些杂质或者缺陷,杂质和缺陷密度的有限性导致了薄膜破坏的概率性。提出了不同尺寸杂质和缺陷分布的分形特征,分析了薄膜破坏概率与辐照激光功率密度的关系,计算结果与实验结果吻合得很好。得到了一种确定薄膜中最具危害性杂质的热学特性及分布密度的方法。同时提出了杂质的敏感尺寸范围(SSR)的概念,由此得到材料激光损伤阈值的新的确定表达式,该表达式反映的损伤阈值与激光脉宽的关系更加符合实验结果。

It is inevitable for films to include inclusions, these inclusions will alter the local electronic field around them in the films when films radiated by laser. In radiating by low power density pulse laser, inclusions are often the original damage sites which initialize break-down of films. Because density of inclusions is finite, damage of films induced by low power laser pulse has character of probability. Fractal distribution character of inclusions with different size has been put forward in this paper. The relation between the probability of damage and the power of laser pulse has been analyzed, a concept of sensitive size range （SSR） has been proposed and results from theory and experiment are identical. It is a base theory for calculating the distribution and density of the most dangerous inclusions in films and the thermal physical parameters of them.